Store-operated Ca2+ entry in rhabdomyosarcoma cells

Rhabdomyosarcoma (RMS), the most common pediatric soft tissue sarcoma, has an intrinsic or early acquisition of resistance to chemo- and radiation therapy. Molecular determinants pivotal for RMS migration, metastatic invasion, cell proliferation, and survival are incompletely identified. Migration and cell proliferation were shown to correlate with cytosolic Ca2+ activity ([Ca2+];). Store-operated Ca2+-entry (SOCE) that increases intracellular [Ca2+] is accomplished by Orail, a pore-forming ion channel unit, the expression of which is stimulated by the transcription factor NF kappa B. The present study explored the expression of Orail and its regulators STIM1 and NF kappa B in human rhabdomyosarcoma cell lines and analyzed their impact on cell proliferation and migration. For the study human rhabdomyosarcoma cell lines RD (embryonal) and RH30 (alveolar) were analyzed for Orai1, STIM1, and NF kappa B transcription by RT-PCR and their corresponding proteins in Western blot [Ca2+]; was detected via Fura-2 fluorescence and SOCE - resulting from [Ca2+] increase following store depletion with extracellular Ca2+ removal and inhibition of the sarcoendoplasmatic reticular Ca2+ ATPase - detected with thapsigargin. Cell migration was analyzed in transwell and mitotic cell death with the clonogenic assay. In summary, Orail, STIM1, and NF kappa B are expressed in embryonal (RD) and alveolar (RH30) rhabdomyosarcoma. SOCE inhibitor BTP2, Orail inhibitor 2 -APB, or NF kappa B inhibitor wogonin virtually abrogated (BTP2, 2 -APB) or significantly reduced (wogonin) SOCE. Moreover, SOCE inhibitors 2 -APB and BTP2 and wogonin significantly inhibited migration and proliferation of both, RD and RH30 cells. These results suggest that Orail signaling is involved in SOCE into rhabdomyosarcoma cells thus contributing to migration, invasion and proliferation. (C) 2016 Elsevier Inc. All rights reserved.